Although it would have been expensive, the US would have been better off to have completed development of both the F-22 and F-23 to keep the contractors putting out their best efforts on price, quality, and schedule. Moreover, even with the F-22 as the preferred type, a relatively small production run of the F-23 would provide US commanders with the relative advantages of both.
In combat, for example, a five to one ratio of F-22s and F-23s would give the US the ability to use the speed of F-23s for a rapid initial contact and missile volley, with the F-22s then arriving in order to use its maneuverability in a dogfight or its larger internal weapons capacity for bombing missions. Having both types available would also complicate mission planning by our adversaries.
Some observers suspect that US built a small number of F-23s for strategic reconnaissance purposes. Or at least that may be why key performance data remains secret for an aircraft that -- officially -- never went into production.
Ah, a fan of Mr. Witcomb I see, ;-) are you aware of the "poor man's area rule" via John Thorp? Google: adverse pressure gradient matching ar-5 to find the link...